A few small families such as the Evaniidae and the Stephanidae are included here, but the vast majority of the group fall into two large families, the Ichneumonidae and the Braconidae, the former distinguished by the presence of two median (or discoidal) cells in the fore-wing (figs.
The ten thousand known species included in this group agree with the Cynipoidea and Chalcidoidea in the position of the ovipositor and in the jointed trochanters, but are distinguished by the fore-wing possessing a distinct stigma and usually a typical series of nervures and areolets (figs.
The fore-wing is generally divided into a firm coriaceous basal region, occupying most of the area, and a membranous terminal portion, while the hind-wing is delicate and entirely membranous (see fig.
Both foreand hindwings are usually present, both pairs being membranous, the hindwings small and not folded when at rest, each provided along the costa with a row of curved hooks which catch on to a fold along the dorsum of the adjacent fore-wing during flight.
The fore-wing also has no stigma, and the whole wing is almost destitute of nervures and areolets, while the pronotum does not reach back to the tegulae, and the feelers are elbowed (fig.